NASA ATTREX: Completes First Science Mission

NASA's unmanned Global Hawk is pushed out of a hangar on Andersen Air Force Base, Guam, in preparation for an ATTREX science flight over the Western Pacific. 

Credit: NASA

NASA's Global Hawk No. 872 completed a 17.5-hour science flight Feb. 14, it's first for the 2014 Airborne Tropical Tropopause Experiment (ATTREX) mission.

The unmanned aircraft, carrying a suite of specialized instruments, flew from Andersen Air Force Base on the island of Guam.

Objectives were to sample vertical distribution of the Western Pacific tropical tropopause layer trace gases, water vapour and clouds.

In situ data was gathered about cirrus clouds in the cold tropopause regions surrounding Guam.

Water vapour concentration was also measured in this area east-southeast of Guam.

To gather these measurements, the aircraft flew an arc first to the northwest of Guam, then reversed course and traveled south and back to the west.

Warren Gore, a researcher from NASA's Ames Research Center, readies the Solar Spectral Flux Radiometer developed by the University of Colorado and NASA Ames for an ATTREX science flight. 

Credit: NASA

The NASA Global Hawk research aircraft is in the Western Pacific region on the ATTREX mission to track changes in the upper atmosphere and help researchers understand how these changes affect Earth's climate.

NASA ATTREX: Climate Change Clues In The Stratosphere

ATTREX is one of the first investigations in NASA's new Venture-class series of low- to moderate-cost projects.

Starting this month, NASA will send a remotely piloted research aircraft as high as 65,000 feet over the tropical Pacific Ocean to probe unexplored regions of the upper atmosphere for answers to how a warming climate is changing Earth.

The first flights of the Airborne Tropical Tropopause Experiment (ATTREX), a multi-year airborne science campaign with a heavily instrumented Global Hawk aircraft, will take off from and be operated by NASA's Dryden Flight Research Center at Edwards Air Force Base in California.

The Global Hawk is capable of making 30-hours of continuous flight.

Water vapour and ozone in the stratosphere can have a large impact on Earth's climate. The processes that drive the rise and fall of these compounds, especially water vapor, are not well understood.

This limits scientists' ability to predict how these changes will influence global climate in the future. ATTREX will study moisture and chemical composition in the upper regions of the troposphere, the lowest layer of Earth's atmosphere.

The tropopause layer between the troposphere and stratosphere, 8 miles to 11 miles above Earth's surface, is the point where water vapour, ozone and other gases enter the stratosphere.

Studies have shown even small changes in stratospheric humidity may have significant climate impacts. Predictions of stratospheric humidity changes are uncertain because of gaps in the understanding of the physical processes occurring in the tropical tropopause layer.

ATTREX will use the Global Hawk to carry instruments to sample this layer near the equator off the coast of Central America.

"The ATTREX payload will provide unprecedented measurements of the tropical tropopause," said Eric Jensen, ATTREX principal investigator at NASA's Ames Research Center in Moffett Field, Calif.

"This is our first opportunity to sample the tropopause region during winter in the northern hemisphere when it is coldest and extremely dry air enters the stratosphere."

Led by Jensen and project manager Dave Jordan of Ames, ATTREX scientists installed 11 instruments in the Global Hawk.

The instruments include remote sensors for measuring clouds, trace gases and temperatures above and below the aircraft, as well as instruments to measure water vapor, cloud properties, meteorological conditions, radiation fields and numerous trace gases around the aircraft.

NASA - Global Hawk

The Global Hawk is a robotic plane that can fly autonomously to altitudes above 60,000 feet -- twice as high as a commercial airliner -- and as far as 11,000 nautical miles -- half the circumference of Earth.

Operators pre-program a flight path, and then the plane flies itself for as long as 30 hours, staying in contact through satellite and line-of-site communications to the ground control station at NASA's Dryden Flight Research Center in California's Mojave Desert.

Image Credit: NASA/Tony Landis